The present invention relates to the field of power generation and storage and, in particular, to an electrolyzer-fuel cell system with increased efficiency.
It is well known that conventional power generating facilities produce more power than is actually needed at most times throughout a given day. This is due, in part, to the fact that it is more cost effective for generators to continue to run at high capacity than to throttle down the amount of power generated, or to completely shut down generators, for the few hours during the day when the demand for electricity is low. Therefore, there is an opportunity to utilize this excess capacity.
A number of prior art systems have been developed to take advantage of this excess power. One type of system, commonly referred to as a potential energy storage system, uses the excess power to store potential energy by pumping water to a higher level for future release through power generating turbines. This system is relatively effective at storing power. However, it requires a large infrastructure, in the form of reservoirs, storage tanks, or the like. Therefore, such potential energy storage devices are not readily adapted to use with many existing power generating facilities. Further, these systems are not readily scalable, as the infrastructure has a finite holding capacity.
Another type of prior art system is commonly referred to as a kinetic energy storage system. One embodiment of this system uses the excess power to accelerate a mass from rest to a high speed, for later coupling to a generator, while another uses the excess power to rotate a massive flywheel to a moderate speed. In each of these embodiments, the inertia of the spinning mass acts to turn the generator to produce electricity. Both embodiments of this system are relatively effective when the storage period is relatively short. However, both of these systems are not effective at storing power for long periods of time. In addition, both are relatively costly, due to the need for costly precision low friction high load bearings to safely support the inertial forces produced by each. Finally, the moderate speed system also requires a significant capital expense, and significant physical space, due to the need for a substantial supporting structure to house the mass.
Still other systems utilize the excess power to charge a chemical battery. These systems store energy in a manner similar to common automotive battery chargers, but utilize vastly more sophisticated batteries that are capable of storing and discharging significantly more power than common lead-acid based automotive batteries. However, these systems have a number of drawbacks that make them undesirable. First, they are relatively large compared to the power that they store. Second, they generally utilize hazardous chemicals, which must be transported, stored and disposed of. Finally, they have a finite number of charge-and-deplete cycles, making them relatively costly.
Another known means for storing power for later use is a regenerative fuel cell, an example of which is found in U.S. Pat. No. 5,506,066. A regenerative fuel cell couples an electrolyzer with a hydrogen fuel cell and is capable of two distinct modes of operation; charging mode, in which electrical energy is consumed and hydrogen and oxygen are produced, and power generation mode, in which hydrogen and oxygen are recombined to produce water and electrical energy is released.
The construction and operation of both an electrolyzer and a hydrogen fuel cell are well known in the art. An electrolyzer typically applies electrical energy to an aqueous solution for the purpose of dissociating molecules to produce hydrogen and other gasses, such as oxygen. One common type of fuel cell includes an anode chamber, a cathode chamber and a proton exchange membrane (PEM), which separates these chambers. Hydrogen is supplied to the anode chamber and oxygen is supplied to the cathode chamber. Electrical energy is produced when the hydrogen and oxygen are combined to form water.
Regenerative fuel cells offer many advantages over the other systems described above. These cells do not require a large initial investment to install, do not require a large amount of space to operate, use non-hazardous materials, will store power for an indefinite period of time, and are, for all practical purposes, infinitely scalable, with excess gas being capable of storage at remote locations, or sold to third parties.
Despite their advantages, the inventor of the present invention has recognized that current regenerative fuel cells fail to capitalize upon the mechanical energy inherent in the production of the constituent gasses. Therefore, there is a need for a system that will fully utilize the benefits of a regenerative fuel cell in order to increase the efficiency of operation of such a cell.
The present invention utilizes a buoyancy engine in to harness the latent potential energy caused by the change of phase from a liquid to a gas produced by an electrolyzer to increase the system efficiency of a regenerative fuel cell. Buoyancy engines are, themselves, well known in the art. On such engine is described in U.S. Pat. No. 4,196,590. However, the combination of a buoyancy engine with a regenerative fuel cell to harness the inherent imparted by the phase change and increase the efficiency thereof is not known in the art.
In its most basic form, the regenerative fuel cell system of the present invention includes an electrolyzing device that is placed in communication with an aqueous solution for converting the aqueous solution into a hydrogen gas. A buoyancy electrical drive is placed in fluid communication with the hydrogen gas produced by the electrolyzing device. This electrical drive includes a means for extracting mechanical energy from the hydrogen gas, and a generator for converting the energy into electrical power. A fuel cell is placed in fluid communication with the hydrogen gas and is adapted to convert the chemical energy in the hydrogen gas into electrical power by combining it with oxygen.
In operation, the electrolyzing device uses electrical energy to convert the aqueous solution into hydrogen gas, which is at an elevated temperature and pressure. The hydrogen, in its gaseous phase, is then transferred by gravity, pressure, or other transport means, to the buoyancy electrical drive. This drive captures the gas and extracts energy from the gas by harnessing the buoyancy force of the gas. This energy is transferred to the generator, which converts the energy in electrical power. Once depleted of its mechanical energy, the hydrogen is transferred to the fuel cell, which combines the hydrogen with oxygen to harness the chemical energy within the two to produce additional electrical power.
In the preferred embodiment of the system, the electrolyzing device also converts the aqueous solution into an oxygen gas and includes a means for separating the oxygen gas from the hydrogen gas.
The preferred means for extracting mechanical energy is a conveyor system that accepts gas into a plurality of closed ended receptacles, such as vanes or buckets, which are attached to, and extend from the conveyor drive. In this arrangement the outputs of the electrolyzer are released at the bottom of a standing liquid reservoir. The gasses, being of much lower specific gravity that the liquid in the reservoir, rise and are caught by the receptacle. The buoyancy force created by the gasses is the exerted upon the receptacle, causing it to rise and, consequently, to move the conveyor drive. The movement of the conveyor drive drives a generator, which converts the mechanical energy into electrical power. Once the receptacle reaches it apex, the gasses are released and are separated and transferred to the fuel cell. In some embodiment, the receptacle is a bucket having a substantially hydrodynamic shape to reduce system drag. In others, the receptacle is a vane, which folds back along the conveyor drive until it reaches its nadir, at which point it unfolds to catch additional gasses and continue the process.
In one embodiment of the system, the means for extracting mechanical energy includes a first bulb in communication with the hydrogen gas, a second bulb in communication with the oxygen gas, a first pulley for transmitting the energy from the first bulb and to the generator, and a second pulley for transmitting the energy from the second bulb and to the generator. In other embodiments, however, only hydrogen is utilized and the means for extracting mechanical energy includes a single bulb in communication with the hydrogen gas and a pulley attached to the bulb and to the generator. In all such embodiments, however, the pulley(s) each produces electrical energy while rising and falling following the release and transfer of the gas to the fuel cell.
The fuel cell of the preferred embodiment also includes a hydrogen storage tank for storing the hydrogen gas for future use in the generation of electrical power. This tank preferably includes a hydrogen outlet for transferring the hydrogen gas from the hydrogen storage tank to a remote location when the hydrogen storage tank reaches a desired capacity.
The system of the present invention may be utilized in connection with other well-known power generation systems such as windmills, solar panels, or hydroelectric systems in order to increase efficiency and feasibility. Geothermal and heat pump technologies, coupled and combined with the system, could increase efficiency and reduce cost when utilized to heat homes with floor radiant heat systems while producing gas for other services. The system could be coupled with many lesser-known polluted water reclamation systems, including devices that make brown gas or gasses that combine hydrogen and oxygen, in order to increase the efficiency thereof.
In addition to its power storage benefits, the system may also be used as a hydrogen production device at times when the hydrogen is not needed to generate power. In this case, once the hydrogen storage tank is filled, additional gas produced by the system will be transferred to storage tanks for sale to commercial hydrogen producers. Such production may also be accomplished by coupling the system with prior art welding machines with carbon electrodes that act as the electrolyzing device.
Therefore, it is an aspect of the invention to provide a power storage system that does not require a large initial investment to install.
It is a further aspect of the invention to provide a power storage system that does not require a large amount of space to operate.
It is a further aspect of the invention to provide a power storage system that uses non-hazardous materials.
It is a further aspect of the invention to provide a power storage system that will store power for an indefinite period of time.
It is a further aspect of the invention to provide a power storage system that is readily scalable.
It is a still further aspect of the invention to provide a power storage system that operates at increased efficiency due to the use of previously untapped mechanical energy.